Toast­mas­ters teaches three skillsets.
By far the best known is public speaking,
but evaluation and leadership are also valuable.
Learning to evaluate a speech teaches you to listen carefully
and to give useful feedback.
The Toast­mas­ters’ Sandwich is the best-known approach:
point out several things the speaker did well,
suggest some areas of im­prove­ment,
and conclude with more praise.

The evaluator benefits too from the evaluation,
as they hone their listening and critical skills
and as they learn to give helpful feedback.
The audience also benefits,
as they hear both the speech
and a measured response to the speech.

Outside of Toast­mas­ters,
feedback is often negative and critical ("Here’s how you’re fucking up"),
which leads to de­mo­ti­va­tion ("I’m just a fuckup!").
For beginning speakers,
who are often horribly afraid of speaking in public,
receiving some positive re­in­force­ment
helps them realize that they already have some skills,
while specific sug­ges­tions can help them improve rapidly.
More advanced speakers who already know their own strengths and weaknesses
often prefer the evaluator to skip a few minutes of praise
and instead provide several very specific sug­ges­tions.
The audience may benefit, however, from hearing the praise,
when the evaluator points out things the speaker did par­tic­u­lar­ly well.

A few clubs also provide a few minutes of open evaluation
where members of the audience speak up and augment the original evaluation.
Freely Speaking Toast­mas­ters does this
and I always find the broader set of per­spec­tives valuable.